Various means have been proposed in the prior art for providing a tow vehicle-trailer combination with an independent braking system. The following prior art patents are illustrative of various trailer braking systems commonly utilized by the industry.
In U.S. Pat. No. 3,790,807, the actuation of the brakes in the trailer is dependent upon the creation of an electrical signal by a transponder connected to receive hydraulic pressure from the master cylinder. The electrical signal is amplified and will actuate a solenoid valve to operate a servomotor in the trailer in synchronization with a braking force supplied the wheel brakes in the tow vehicle.
In U.S. Pat. No. 3,856,363, the actuation of the brakes in the trailer is dependent upon the creation of a pneumatic signal in the tow vehicle. The pneumatic signal is transmitted through a conduit to operate a servomotor in the trailer in synchronization with the actuation force which operates the wheel brakes in the tow vehicle.
In U.S. Pat. No. 3,880,263, the actuation of the brakes in the trailer is dependent upon a difference in the rate of deceleration between the tow vehicle and the trailer. The differential in the rate of deceleration is utilized to compress a piston in a master cylinder associated with the tongue connector of the trailer. The master cylinder supplies the wheel brakes in the trailer with an actuation force.
In some applications, the cost of providing an electrical transducer means as taught by U.S. Pat. No. 3,790,807, a pneumatic signal producer, as taught by U.S. Pat. No. 3,856,363, and a tongue with an integral master cylinder as taught in U.S. Pat. No. 3,880,263 is not justified because of the type and use of the trailer.